Thread tensioning device for a shirring attachment for sewing machines



Apnl 14, 1959 w. C. CREMER ETAL 2,881,724

THREAD TENSIONING DEVICE FOR A SHIRRING ATTACHMENT FOR SEWING MACHINES Filed July 21, 1955 .3 Sheets-Sheet l INVENTORS creme r ATTORNEYS WTEZ,Bu&e z

c CREMER ONING DE ATTACHMENT FOR SEWING MACHINES 2,881,724 RING April 14, 1959 w. ET AL THREAD TEN-SI VICE FOR A SHIR Filed July 21, 1955 3 Sheets-Sheet 2 INVENTORS C10 heme 1 ATTORNEYS United States Patent THREAD TENSIONING DEVICE FOR A SHIRRIN G ATTACHMENT FOR SEWING MACHINES William 'C. Cremer, Reading, and William E. Bubel, Tamaqua, Pa.; said 'Cremer assignor to said Bubel Application July 21, 1955, Serial No. 523,450

2 Claims. (Cl. 112-101) This invention relates to sewing machines, and more specifically to an attachment therefor especially designed v for effecting a shirring of fabric goods as the goods are chain stitch which can be applied to practically any commercial or industrial sewing machine now available on the market, the attachment being adapted to apply a resilient strand, cord or strip, to a sheet of non-elastic fabric, the resilient element being applied to the fabric 2,881,724 Patented Apr. t 1959 is mounted on one end of a shaft 28 and is secured thereto for rotation therewith by a set screw 30. The shaft 28 is supported between a pair of journals 32 which are secured by screws 34 to an elongated substantially rectangular side plate 36 which is, in turn, detachably mounted by conventional means in an elongated slot 38 formed in the base plate 40 of the sewing machine 10. Y A disc 42 is secured to the other end of the shaft 28 by means of a set screw 44.

The disc 42 is provided with a laterally extending offset boss 46 having a laterally extending crank pin 48. The crank pin 48 is embraced within a pair of bearing sleeves 50, 52 disposed within the oppositely disposed, substantially semi-circular split bearing members 54, 56, the latter being joined together by bolts and nuts'58,-60 which extend through confronting flanges 62, 64.

The bearing member 56 is provided with an integrally formed, radially extending, internally threaded sleeve 66 which is adapted to receive one externally threaded end of a shaft 68. The other end of the shaft 68 is also externally threaded and is received in an internally threaded sleeve 70 which terminates at its other end in an enlarged sphere or ball 72. The ball 72 is received within asplit bearing socket including the confronting members 74, 76

under tension, whereby, upon release of the tension, the

fabric will present a rufiied or shirred appearance.

Another object of this invention is to provide means for securing an elastic thread or cord to the back side of a strip of fabric material being sewed with a multiple needle sewing machine sewing a chain stitch, the cord being disposed between the needle and the looper threads of the stitch on opposite sides of the needle at each successive stitch.

Other and further objects and advantages of the instant invention will become more evident from a consideration of the following specification when read in conjunction with the annexed drawings, in which:

Figure 1 is a side elevation of a conventional multiple needle sewing machine for sewing a chain stitch, and including an attachment for laying and attaching an elastic thread or cord to a piece of fabric material.

Figure 2 is a top plan view of the device shown in Figure 1.

Figure 3 is a partial transverse cross-sectional view of the sewing machine and attachment, certain parts thereof being broken away.

Figure 4 is a fragmentary detail cross-sectional view.

Figure 5 is a fragmentary cross-sectional view taken on the horizontal plane of line 5-5 in Figure 1, looking in the direction of the arrows.

Figure 6 is a fragmentary cross-sectional view taken on the vertical plane of line 6-6 of Figure 2, looking in the direction of the arrows.

Figure 7 is a fragmentary detail cross-sectional view taken on the vertical plane of line 7-7 of Figure 2, looking in the direction of the arrows.

Figure 8 is a detail cross-sectional view.

Figure 9 is a schematic view of a chain stitch having an elastic thread or cord incorporated therewith in accordance with the present invention.

Referring now more specifically to the drawings, reference numeral 10 designates, in general, a conventional multiple needle sewing machine. The sewing machine 10 is provided with an electric motor 12 having a drive shaft 14 on which is mounted a pulley 16 for driving the conventional sewing machine mechanism. The drive shaft 14 carries an extension 18 on which is mounted a V-pulley 20 secured thereto by set screw 22. An endless V-belt 24 connects the pulley 20 with a second V-pulley 26 which which are secured together as by the bolts 78. The split bearing members 74, 76 are disposed at one end of a lever 80 having its other end fixedly secured to the upper end of a shaft 82 by means of the set screw 84. The shaft 82 is rotatably mounted within an elongated vertically extending circular passage 85 extending transversely through a journal block 86 secured to the base plate 40 by the screws 88.

The journal block 86 is provided with an inverted substantially U-sh'aped recess 90 extending inwardly from the lower end thereof and receives therein a reduced diameter depending portion 92 of the shaft 82. The depending portion 92 of the shaft 82 is fixedly secured by set screw 94 within a passage 96 formed in one end of a throw-block 102, the throw-block 102 being bifurcated at its other end to provide a pair of throw-bars 104, 106. The throw-bars 104, 106 extend transversely across a reciprocating bar 108 and alternately engage opposite sides of an enlarged head 110 of a bolt 112 threaded into the bar 108. The bar 108 extends longitudinally of the base plate 40 between a pair of guide rails 113,-114and beneath a cover plate 116. The guide rails 113,114 and cover plate 116 are secured to the base plate 40 as by the screws 118.

The other end of the bar 108 is disposed adjacent to and in confronting relationship with respect to the presser foot 120 and is provided with a plurality of spaced transversely extending passages 122, each of which is adapted to slidably receive therethrough an elastic thread or cord 124.

The elastic threads 124 are fed upwardly from a source of supply (not shown) through a pair of racks 126 and 128. The rack 126 depends from the base plate 40 at one side of the sewing machine 10 and is secured thereto by any conventional means. The rack 126 is formed of a pair of side members 130, 132 connected at their lower ends by a cross-member 134. A plurality of elongated cylindrical rods 136 extend horizontally of the rack 126 in vertically spaced relationship, and have their opposite ends supported in the side members 130, 132. The side member 132 is provided, adjacent its lower end, with a pair of arcuately shaped, spaced lateral extensions 138, 140, which are adapted to serve a function to be described.

The rack 128 comprises .a pair of side members 142, 144 and the upper ends thereof are pivotally mounted on the uppermost of the rods 136. The side members 142, 144 engage the opposite ends of a plurality of elongated,

ff "agate-litan aratgad' substantially cylindrical a 146, which are vertically spaced and are so arranged as to be staggered with respect to the rods 136. A knurled nut 1 48jhayi-ng an enlargedflange 150, is threaded into 7 the iflowefwndf'of theside member 144 with the shank portion 152" thereof extending between the arcuately shaped lat- .Qeralexte'nsions 138,- 140. Thus it is seen that the rack 8, being journalled in split bearingmembers 54, 56,

:ggmparts'an arcuate and reciproca'ting aetion to the shaft 68 which, in t'urn, oscillates the lever 80 through the uni- ;yersal connectioniwhich includes the A members 72, 74 and 76, The sh'aft 82 having the lever 80'secured thereto T is thereby'givfin n Scillat0ry, movement therebywhich is imparted to the throw-block 102 ,to effect an engagef inent of "the bifurcated arms 104, 106 alternately, and f;in,0pposi te-'directions, upon the enlarged head 1100f "the bolt 112. Thisaction produces a reciprocating move- "naent of the bar, 108 longitudinally of the base plate 40 'i'whereby the elasticgthreads 124 are moved to opposite i sides of the needles 154' on each successive stitch. ,Thus, it'flWill-be seenthat as the non resilientffabric 156 is f passed-transversely across-the base plate ,40 beneath the pressure -foot,-120, the needles 154will-forma chain ;stitch- ;1581-attaching thev elasticxthreads '124-to: the back f side ofi the "fabric;156 with the-elastic threads-124 being disposed between the needle thread 160 and'the looper thread 162; as i'llustrat'edin Figure 9 :of the-drawings. As stitching'proceeds; and the fabric is released fro'm beneath--the'- pressure foot 120, the fabric 156 is placed under tension by" the elastic threads 124 "and assumes theshirredappearance designated by the reference numeral 156 in Figure 4'of the'drawings.

"It'isto ,be 'understood"that"the threads '124are first pre-ten'sioned bytheir'threaded engagement with alternate'sides'ofthe' racks '126'"and 128,and' the proper pretensioning-stressis placed thereon by the "displacement of the rack *128 relative to the rack '126. p

Having described anddllustrated one embodiment of f this""inventi onin detail, it-is' to be understood that-the "same "is-'"o'fier'ed' merely by way of example; and-"that racks together in a plurality of adjusted positions with n relati IQ: sas eth y lsrsb with threads; 'lying btween said first and second' plurality of rods and enthe invention is to be limited only by the scope of the following" claims.

What is claimed is:

l. A multiple thread tensioning device for shirring attachments to multiple needle sewing machines comprising a vertically disposed rack adapted to be detachably secured rigidly to said s ew'iiig-machine, said rack including a; pair of uprig ht; sidemembers, a plurality of horizontally disposed vertically qspaced parallel was" having their opposite ends supported in said side members, a second racli i ncl udihg a second paiif or ght sidemembers, said"second"paiiof side members having their upper endsjjournalled* onthe uppermost of the parallel rods in said first raclc, a second plurality of horizontally disposed vertically spacedparallel rodshaving their opposite ends supported in said sec-0nd pair of side members, said second plurality of rods being alternately positioned between the rods of said first plurality withsaid'second e s iwui i th 's ti a B Y dia 's 's i first rack, and means on said racks for releasably securing said gaged oppositely by of each rack the tension on said threads be adjustedby adjusting said' second rack relative to said firstrack,

v 2. A device as claimed in claim 1 wherein the means fsecuring raclss together comprises a pair ofarcilate spaced apartgei lerz tlly parallel rigid'exteusions mounted on the other of saidracks for movement beirit e grally f ormed on one of said racks, and a screw clamp tween "saidfiitens idns f with said" screw clamp being adapted to clamp said io thcr raclc to said extensions in aplurality of adjusted positionsthereon. 

